|Manganese is more electropositive than its neighbours in the periodic table, but despite this manganese react with air at room temperature very slowly. Heated manganese powder can react with oxygen and nitrogen from the air with subsequent formation of manganese oxides with different oxidation state, mainly Mn3O4 and MnO2 and manganese nitride Mn3N2. At room temperature very slowly reacts with water:|
Mn + 2H2O -> Mn(OH)2 + H2
Manganese easily reacts with common acids, like sulphuric acid or hydrochloric acid with formation of Mn2+ ions. Mn2+ ions in aqueous solution are presents as a aquated colourless complexes [Mn(OH2)62+
Liquid Manganese can produce carbides (Mn3C), electrically conductive silicides (Mn3Si), different borides (for example Mn4B), phosphides (for example Manganese monophosphide MnP).
Manganese oxidation states are +2, +3, +4, +6 and +7 (+1 and +5 very unusual) and therefore manganese can formate following oxides: MnO, Mn2O3, MnO2, MnO3 and Mn2O7. MnO3 was newer separated. Mn2O7 is a very aggressive liquid, which is unstable at high temperatures and can explode.
Another very important manganese compounds is manganate - compounds that contains the tetrahedral manganate ion MnO42-. MnO42- ion is paramagnetic. Also magnesium (Mn7+) can form Permanganates, a strong oxidizing agents.
Basic chemical reactions for manganese:
3Mn + 2O2 -(t)-> Mn3O4
3Mn + N2 -(t)-> Mn3N2
Mn + 2H2O -(t)-> Mn(OH)2 + H2
Mn + Cl2 -> MnCl2
Mn + Br2 -> MnBr2
Mn + I2 -> MnI2
Mn + F2 -> MnF2
2Mn + 3F2 -> 2MnF3
Mn + 2H2SO4(conc.) -> MnSO4 + SO2 + 2H2O
3Mn + 8HNO3 -> 3Mn(NO3)2 + 2NO + 4H2O